There are two general objectives of this project. One is to obtain a better understanding of the antigenic determinants of the major allergen of ragweed pollen, antigen E, so that we may know better how to prepare detoxified allergen derivatives which can be of potential use for the desensitization of patients. It is toward this objective that various chemical modifications of antigen E will be carried out. The other objective is to study the chemistry of bovine plasma albumin so that we may have a better understanding of its organic ligand binding properties and its antigenic determinants. The approach taken will be to cleave albumin molecules into large fragments by chemical and/or enzymatic means then to examine these fragments for their binding or antigenic properties.